The invention relates to a conveyor for the stepwise advance of a vertically parted boxless mould through a pouring and cooling zone of a guideway having mould carrying bottom rails and longitudinally movable side rails arranged for the gripping and stepwise advance of the mould under permanent squeezing of said mould in its transverse direction.
The Danish patent specification No. 119 373, for instance (corresponding e.g. to U.S. Pat. specification No. 3,744,552) discloses a mould conveyor in which the two sides of the guideway are constituted of a pair of parallel rails connected with a common reciprocating mechanism, at least one of said rails being, concurrently with its longitudinal movement, transversely movable into and out of engagement with the mould. The advance of the mould can be derived solely from the two parallel rails, or these rails may supplement a conveying force exerted on the mould by one of the pressing plates used to successively compress the mould parts.
In this known conveyor, the two rails must during their conveying strokes exert strong opposite lateral pressures on the mould for its advance, while the mould must be entirely or substantially relieved from pressure during the reversing stroke of the rails. The mould is thereby subjected to alternating transverse and longitudinal loads which may cause minor deformations detrimental to the accuracy of the manufactured castings, and the fact that the conveyor cannot exert a permanent transverse squeezing of the mould, as stated above, can thus be regarded as a drawback of said conveyor.
Such a transverse squeezing or transverse compression is rendered possible by a conveyor as known from DE-C No. 27 27 867 for the same utilization, the guideway sides in this case being constituted of vertical plates or shields carried by circulating, stepwise running chains, the paths of movement of which are determined by stationary guiding rails. Compression springs holding the plates fixedly abutted against the sides of the mould are inserted between the chain links and the plates.
In order to allow the circulating movement, the length of the plates in the direction of movement cannot be substantially larger than the axial thickness of a single mould part, and for the same reason, the plates must necessarily, via their connection with the chains, be mutually pivotable about horizontal axes. Furthermore, the centre of the surface pressure between a pair of opposite plates and the mould part held therebetween is at substantial height above the stationary guideway bottom which exerts a very important friction against the conveying of the mould. All this results in the individual mould parts being subjected, during each advance stroke, to a couple (the conveying force from the plates and the braking frictional forces) and therefore having a tendency to tilt forwards. This may cause minor vertical displacements between the successive mould parts, thus in the joints where the pouring cavities are positioned, and there is therefore a risk of flaws as a result of a displacement between the portions of the same pouring cavity contained in their respective mould part.